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Discussion Starter #1 (Edited)
Good morning y'all

I haven't been on here for a while. I have a friend's Vstar 1100 custom, I think it is a 2006. Out of nowhere yesterday after a 200 mile ride it began to run on one cylinder. After we got it back to my house I took it for a ride and found on idle and to about 10 MPH both cylinders were firing. after 20 MPH 1 cylinder would drop off. I figured out the rear cylinder seems to be the culprit.

I do not have a timing light so I cannot say with 100% certainty that it is a spark issue, but that seems most likely to me.

I was hoping that someone else may have experienced the same symptom and figured it out. I hate to have her buy a coil and find out that is not the problem. It could be the igniter which would be pretty pricey obviously.

Now I suppose it could be a carb issue, but that does seem less likely to me, especially the way it came on so suddenly.

And suggestions appreciated. Not a mechanic here , just have done allot of basic repairs, but not a professional wrench by any means

Thanx

Happy 4th of July weekend

DOC
 

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Take it from somebody who had the exact same problem and went the "must be an ignition" issue route first. Remove the carbs and clean them. It only takes one little piece of junk to clog the main jet and then your problem has arisen.

I replaced the Rectifier, plugs and coils and still had the issue. Pulled the carbs and the rear carburetor was filthy and the main jet was clogged. Cleaned it all up and the issue was gone after about 10 minutes of riding to get the gas flowing into all the right places.

It should also be mentioned that you should make sure the fuel filter and fuel pump are nice and clean/flushed. And that there's no sediment in your gas tank from possible rust. :)

In case you want to read about my journey : http://www.starbikeforums.com/forums/showthread.php?t=69578

GL!

eGo
 

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Discussion Starter #3
Hey eGo

So you had the same issue, out of nowhere low speed/RPM both cylinders fired then past a certain point the other cylinder did not?? MAN, I HATE pulling these freakin carbs!! My fingers don't get in there so good!! She had it rejetted and cobra pipes put on about 2K miles ago last season. Doesn't seem like it would get so clogged up so fast. I was thinking about trying some seafoam or Marvel Mystery oil. Wish I had a good timing light I could mount to verify good spark.

Thanks for the information

Not doing anything on it today, have a brake job to do on my brother's truck first.

In the meantime anyone else that wants to chime in on their opinion I'm all ears. It will be a few days before I can do anything on it, so trying to research the problem first

Thanks again
DOC
 

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Mine wasn't out of nowhere, at least not for me. I bought it that way. But, the majority of the cases where people have had this issue end up being carb related. Is it possible that a coil or the CDI or stator have failed? Yes, it's possible. You're going to have to take the tank off to test the coils anyways, so you're already pretty much to the point of removing the carbs. I'm not going to say "don't" test the other stuff while you're there. I actually did test my coils and they were showing out of tolerance, so I replaced them with some used ones that were still "out of tolerance" but much closer than the stock ones. I had the same issue afterwards. Basically what I'm saying is that it's possible for things to "look" bad but not "be" bad.. And before I threw any money at it, I'd clean the carbs out and see what you get. I don't know how long the off season is for riders where you are but if your friend didn't put some kind of fuel stabilizer in the gas it's possible that things got a little gummed up over the winter and something broke loose on the long ride and clogged up the jet.

It's amazing how much of a difference that one cylinder makes. These bikes aren't anywhere near as much fun on one cylinder as they are on two. I was amazed at the difference. And it also sucked only being able to do 60mph in 5th gear at WOT.. lol

GL!

eGo
 

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Discussion Starter #5
Oh yea, 1 cylinder dead makes it like a freakin minibike!!

But ya her's came on very suddenly after running fine, that's why I am more inclined to think it is electrical, but at this point I realize it could be ANYTHING spark or fuel related!! Just trying to narrow down the possibilities. I have found that unless a cylinder is just dead all the time, the checks they give you with an ohm mneter are of minimal help, they can read way out of spec and work fine!! In the meantime whatever I do find I will post on here
Thanks
 

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1.) Swap the coils...if the problem moves to the front it is electrical .....if the rear cylinder is still dead.....

2.) Clean and synch your carbs. If the bike sat for any length of time, especially if no fuel stabilizer was used....the carbs are the issue.

....my bet is that it's the carbs.
 

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Discussion Starter #7
The coils can't be swapped, they have different length wires that are part of the coil. May well be the carbs, I tried it again today and found that in 2nd gear it would start to run on 1 cylinder at around 30 MPH but if I put the choke to half on it would make it to 40 MPH. I am not certain, but I do not think the choke would effect it if it was the coil. Strange that it came on so suddenly, but I suppose a piece of guck could have gotten by and jammed up a jet somewhere
 

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One time I rode to the store and parked. ('06 1100) Bike was fine. Came out of the store, fired it up and noticed a little "pop" when it started, started running on front cylinder only. Nursed it a mile to home. Found the boot on the back carb popped off, possibly from a small backfire.
 

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Discussion Starter #9
Ya know that happened to me on my 87 virago 1100 too!! Can't believe I did not think of that to check!! I will check that tomorrow!! Thanks!! I will update this thread whether it helps or not!!

PEACE
DOC
 

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Discussion Starter #10
Well checked the carb boots, no issues there, sprayed all around them with brake cleaner and no variance on Idle. Checked coil and cleaned ground connection and retightened it. Pulled plugs and they both look decent. Also found that if I go to 30 MPH in 2nd it loses rear cylinder, but if I then choke it halfway, it gets to 40 MPH, kinda makes me believe more that it is a carb issue. I also checked voltage and it is 14.0 at idle and goes up to 14.3 when I increase throttle, so stator and regulator are OK
 

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If you have a chance to post audio/video of what it sounds like, that would be the best way for me to suggest possible problems/solutions... I'm better "by ear" than by reading...
 

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Discussion Starter #12
Update, tried turning petcock off till bike ran out of gas. Then put petcock back in the on position and ran the bike. Got 2 cylonders for a half mile, then back to 1 cylinder. Repeated several times, same thing. Think I will try the fuel filter just for giggles before pulling the carbs
 

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Discussion Starter #13
If you have a chance to post audio/video of what it sounds like, that would be the best way for me to suggest possible problems/solutions... I'm better "by ear" than by reading...
I will not be working on it again till wed or thurs, but I will try to get a video. I can tell you that the rear cylinder drops off at about 20 MPH in 1st and if I give half choke it gets to 30. Then you get that "lawn mower" sound of one cylinder working and one not
 

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Voltage at an idle should be around 12.8....14+ is too high. If it really is 14v at idle...your reg/rec is toast and should be replaced right away....it could take out every sensor and electrical component because the voltage will keep increasing.

You need to unbolt the coils, ground them and put the wires on the appropriate plugs.... easy 5 minute test.... sometimes you have to think around a problem a little bit. That'll tell you for sure if it's a coil issue...(which I highly doubt---but you never know until you test it)

Take the carbs off and clean them up...run a bread tie wire through all the holes in both the pilots and mains. Check the floats. Check the needles.... one could have popped out of the holder....and etc etc etc.... it's pretty easy to get them off and on.
 

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If you plan to poke anything through the holes in the jets, I suggest you don't use anything metallic. Use various sizes of monofilament fishing line or nylon guitar strings. It is possible for anything metallic to damage the jets, while the plastic fishing line won't.
 
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